CVE-2026-86469
Description
A flaw was found in GLib2. When g_file_replace() is used with G_FILE_CREATE_REPLACE_DESTINATION and creating the .goutputstream-XXXXXX temporary file fails, the library unlinks the destination and recreates it without exclusive creation or symlink protection. A local attacker who can write to the destination directory can win that race and redirect the write to another file.
Statement
Exploitation is local, requires write access to the destination directory, requires the uncommon temp-file fallback in handle_overwrite_open(), and requires winning a race. The usual g_file_replace() path writes to a temp file first and is not this bug. A successful race can overwrite or create a file the victim process is allowed to write.
Mitigation
Do not use g_file_replace(..., G_FILE_CREATE_REPLACE_DESTINATION) on paths in directories writable by less-privileged users.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 5.3 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | High |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | High | N/A | High |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L
cve.org: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L
Understanding the Weakness (CWE)
Confidentiality,Integrity,Access Control
Technical Impact: Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism
An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.
Other
Technical Impact: Execute Unauthorized Code or Commands
Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.
Acknowledgements
Red Hat would like to thank Aisle Research for reporting this issue.
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